Physiological Responses of Juvenile Rainbow Trout to Fasting and Swimming Activity: Effects on Body Composition and Condition Indices

Possible Seasonal Population Bottlenecks In Brook Trout (Salvelinus fontinalis) in Central Appalachian Headwater Streams

“…Therefore, it is not surprising that we observed little depletion in fat content under laboratory winter conditions. Further, mean fat estimates of our wild brook trout ranged from 0.9 to 3.7 g, levels well above the 0.2 g of fat that were related to mortality of similar sized rainbow trout (Simpkins et al 2003). Brook trout under simulated winter conditions changed little in dry, protein, and fat weights.…”

“…The trout in our experiment were relatively sedentary due to the lack of any substantial flow in the experimental tanks. Sedentary juvenile rainbow trout at 4O C did not show any mortality and showed little lipid loss over a nine week period (Simpkins et al 2003). Lipid loss was also minimal in starved trout over a 45-day period (Denton and Yousef 1976).…”

“…Wild brook trout fkom all streams were above the critical mean fat level of 0.2 g [determined by Simpkins et al 2003, using 120-142 mm TL juvenile rainbow trout (Oncorhynchus mykiss)] in pre-winter and post-winter sampling periods (Fig. 4).…”

Energy allocations to xenobiotic transport and biotransformation reactions in rainbow trout (Oncorhynchus mykiss) during energy intake restriction

“…These results are in agreement with other literature on feed-deprived rainbow trout, in which BW decreased within 4 to 6 weeks, and reductions in LSI became significant within much shorter time frames (2 days to 3 weeks of dietary restriction) (Farbridge and Leatherland 1992;Vigano et al 1993;Blom et al 2001;Mattson et al 2001). The rapid change in LSI in early fasting is likely due to a cortisol-induced mobilization of liver glycogen and lipid stores; as trout fasted for 3 to 4 weeks exhibit enhanced gene expression of key enzymes in gluconeogenesis, and a down-regulation of glycolysis and the pentose phosphate pathways (Blom et al 2000;Simpkins and Hubert 2003;Johansen and Overturf 2006;Salem et al 2007). As the body adjusts to long-term fasting, visceral fat and muscle lipid stores begin to be catabolized for maintenance energy in preference to exhausting hepatic lipid stores; this can be exhibited as a resistance to further reductions in LSI that have been noted in past studies, and in the present study appears as little reduction in mean LSI of fasted fish after week 3 (Adams and McLean 1985;Farbridge and Leatherland 1992;Simpkins and Hubert 2003;Salem et al 2007).…”

Effects of Acid Rock Drainage on Stocked Rainbow Trout (Oncorhynchus mykiss): An In-Situ, Caged Fish Experiment

“…Fasting studies utilizing juvenile rainbow trout demonstrate severe physiological responses only after substantially longer fasting periods (Simpkins, Hubert, Del Rio, & Rule, 2003).…”